Hydraulic lash adjuster

ABSTRACT

In a hydraulic lash adjuster having a plunger which adjusts for taking up slack in the valve train, a cup element is positioned in the plunger cavity for reducing the pressure in the adjuster reservoir. A restricted passageway is formed by the cup wall directing flow from the inlet both into the reservoir and up toward a lip of the cup thereby reducing the reservoir pressure relative to the inlet pressure. The cup lip includes a groove forming a restricted meter passageway between the closure element opening and the cup lip periphery.

United States Patent 1191 1111 3,838,669

Dadd Oct. 1, 1974 [54] HYDRAULIC LASH ADJUSTER 3,630,179 12/1971 Dadd123 9035 [75] Inventor: Morris V. Dadd, Muskegon, Mich.

Przmary Exammer-Charles J. Myhre [73] Assignee: Johnson Products Inc.,Muskegon, Assistant E i r R H Lazarus Mich- Attorney, Agent, orFirmPrice, Heneveld, Huizenga 22] Filed: Aug. 11, 1972 & Cooper [21]Appl. No.: 280,063 [57] ABSTRACT In a hydraulic lash adjuster having aplunger which ad- [52] US. Cl. .123/9035, l84/6.9 justs for taking upslack in the valve train, a cup [51] Int. Cl. FOlm 9/10 ment ispositioned in the plunger cavity for reducing [58] Fleld of Search123/9035 90-43; 84/69 the pressure in the adjuster reservoir. Arestricted passageway is formed by the cup wall directing flow from [56]References (mad the inlet both into the reservoir and up toward a lip ofUNITED STATES PATENTS the cup thereby reducing the reservoir pressurerela- 2,964,027 12/1960 Dadd 123/9035 tive to the inlet Pressure The p pincludes 11 3,153,404 10/1964 Van Scooten groove forming a restrictedmeter passageway be- 3,267,918 8/1966 Ayres tween the closure elementopening and the cup lip pe- 3,448,730 6/1969 Abell, Jr. riph ry3,476,093 ll/l969 Line 3,598,095 8/1971 Ayres 123/9035 12 CIaImS, 5Drawmg gu HYDRAULIC LASH ADJUSTER BACKGROUND OF THE INVENTION Thisinvention relates to hydraulic lash adjusters, and more particularly toa novel lash adjuster which features an oil pressure reduction meansthat also meters the flow of lubricating oil through the adjuster.

Present high speed engines are beginning to use overhead camshaft enginedesigns to reduce the weight of reciprocation. This permits a higherspeed operation while maintaining full control of the valve trainoperation. The reduction in reciprocating weight results in the load onthe lash adjuster being considerably lighter when compared to a standardpush rod type seat. Consequently it is desirable to reduce the oilpressure supplied to the lash adjuster in order to reduce the pumpupeffect. There is also a need for a simpler and more economical means toprovide a positive rate of oil flow through the adjuster to lubricatethe rocker arm socket which is in receipt of the upper end of the lashadjuster. Thus, it is desirable to provide an economical means formetering the flow of lubricating oil in addition to reducing the oilpressure in the lash adjuster itself.

SUMMARY OF THE INVENTION A conventional lash adjuster includes a bodywith a reciprocating plunger movable in the body. The plunger has acentral cavity portion defining an oil reservoir and inlet portsthroughthe body and plunger to supply oil to the reservoir. The upperend of the plunger is closed by a closure element which in the overheadarrangement includes a fulcrum ball seated in the socket formed in therocker arm. In a tappet utilizing a push rod, the closure elementdefines a push rod seating means. The closure element includes a centralpassageway to permit the injection of lubricating oil from the reservoirto the rocker arm.

In accordance with the invention, means are provided in the plungercavity to form a restricted passageway at the inlet port to direct theflow of oil through the inlet port both into the reservoir and up towardthe closure element. This reduces the reservoir pressure relative to theinlet pressure. The lower reservoir pressure allows the desired higherspeed operation in the engine.

In a narrower aspect, a cup-shaped element having a lip extendingradially from its open end is positioned in the cavity adjacent theinlet port. The cup wall diameter is less than the inner diameter of theplunger cavity at the inlet port to form the restricted passageway. Thecup is positioned by an interior shoulder which holds the cup lip. Thereservoir pressure however acts on the bottom of the cup to urge the cupoff the shoulder against the closure element thereby permitting the flowof oil around the cup lip. The lip includes a groove means forming arestricted oil flow passageway to the central opening of the closureelement from metering the rate of lubricating oil flow to the rocker armsocket.

The reduction in reservoir pressure relative the adjuster inlet pressurein accordance with the invention provides a unique relativelyinexpensive construction for reducing the pump-up effect. In addition, apositive metering of the oil flow is achieved with the same element.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representationpartially in cross-section of an overhead cam valve train having a lashadjuster according to the invention;

FIG. 2 is an enlarged cross-sectional view of the lash adjuster shown inFIG. 1;

FIG. 3 is a plan view of the cup shown in FIG. 4;

FIG. 4 is a fragmentary cross-sectional view in elevation of themetering cup provided by the invention; and

FIG. 5 is an enlarged cross-sectional view similar to FIG. 2 of analternative embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT Briefly, a preferred applicationof the invention relates to usage in an overhead lash adjuster utilizinga movable closure element engageable directly with the rocker arm.However, the concepts are equally adapted in a tappet constructionutilizing a closure element having a push rod seat engageable with ahollow push rod anchored to the rocker arm. Both applications arediscussed separately below.

OVERHEAD LASH ADJUSTER Referring now to the drawings in detail, FIGS. 1and 2, show a valve 2 having a spring 4 and retainer 6 actuated byrocker 8 through a camshaft l0 and cam 12. The rocker arm 8 pivots abouta socket 14 on lash adjuster 16. The lash adjuster, which automaticallyadjusts for lash, contains a body 18 with a plunger 20 having aninternal cavity 22 which opens into a bottom compression chamber throughcheck-valve plate 24. The upper open end of plunger 20 is closed by aclosure element 26 which along with plunger 20 is biased in the upwardposition against the closed socket 14 of rocker arm 8 through a spring28. A spring 30 biases valve plate 24 against the bottom of plunger 20.A valve retainer 32, which holds the check-valve assembly in place, isheld against the bottom of plunger 20 by spring 28.

Lubricating oil enters cavity 22 through ports-34 and 36. As isconventional in hydraulic valve lifter assemblies, the oil passesthrough cavity 22 through the bottom portion of plunger 20 into thebottom compression chamber. Cavity 22 forms an oil reservoir. Thereciprocal motion of plunger 20 in body 18 is limited at the lowerextremity by a shoulder 38 and at the upper extremity by a retainer ring40 which clips over the upper end of body 18 and is engageable in theextreme position by a shoulder 42 of closure element 26.

Referring now in greater detail to FIG. 2, the counter-bore of plunger20 which defines cavity 22 includes an internal shoulder 44 which actsas a stop for metering cup 46. Cup 46 includes a bottom wall 48 and anannular sidewall 50. The upper end of sidewall 50 is formed into anoutwardly projecting annular lip 52 which under certain conditions willseat on shoulder 44, the shoulder acting as a stop for further downward.

movement of cup 46. The outer diameter of lip 52 is less than that ofthe plunger wall to permit oil to flow around the lip as required.Shoulder 44 is positioned slightly above inlet port 36 so that when cup46 is positioned within cavity 22, wall 50 extends over inlet port 36.The outer diameter of wall 50 is less than the inner diameter of cavity22 at inlet port 36 so that a restricted passageway 54 is formed atinlet port 36. The significance or restricted passageway 54 will bedescribed hereinafter.

The closure element 26 includes a main body portion 56, the lower end ofwhich is receivable in plunger cavity 22. Closure element 26 includes acentral opening 58 which extends longitudinally through closure element26. The cross-sectional configuration of opening 58 is enlarged at thelower end of closure element 26 with its axial depth correspondinggenerally to that portion of closure element 26 which is telescopedwithin plunger 20. The lower end of closure element 26, which is open,forms an annular seat 60. Shoulder 42 is positioned so that there is aminimum spacing between the lower end 60 of closure element 26 andinternal shoulder 44 which exceeds the thickness of lip 52. When cavity22 is filled with oil, the oil pressure therein will push metering cup46 up off shoulder 44 into engagement with the lower end or seat 60 ofclosure element 26. This configuration permits the flow of oil beneathand around lip 52 over shoulder 44.

A groove 53 is formed in the lip portion 52 of cup 46 to permit flowcommunication from the inlet 36 or reservoir 22 into the central opening58 of closure element 26. By careful selection of the cross-sectionalflow area of groove 53, the rate of flow through the adjuster can bemetered. It will be appreciated that a groove could be formed in thelower end of the closure element as an alternative to that in the lipportion.

The upper end 62 of closure element 26 has a spherical configuration toform a fulcrum ball receivable in socket 14 (FIG. 1) of rocker arm 8.The fulcrum ball 62 is retained in socket 14 by a spring clip 64, thelower end of which snaps into an annular retaining groove 66 formed inbody 56 of closure element 26. As oil is metered through central opening58 of closure element 26, it will be directed onto the surfaces ofengagement between fulcrum ball 62 and socket 14. An oil bleed port 68is provided through rocker arm 8 and aligned with central opening 58 tofacilitate the passage of lubricating oil through the lash adjuster.

OPERATION During the engine operation, lubrication oil is brought intothe plunger cavity 22 through ports 34 and 46. Since the outer diameterof wall 50 of metering cup 46 is less than the inner diameter of cavity22 at the inlet side of port 36, the oil pressure will cause the cup toposition itself away from the inlet in abutment with the inner wall ofthe plunger opposite inlet 36. This will define a restricted passageway54 which extends both downwardly into the plunger cavity or tappetreservoir 22 and upwardly toward cup lip 52. Since the oil pressure incavity 22 acting against the bottom wall 48 of cup 46 will cause the cupto move up into abutment with the bottom surface or seat 60 of closureelement 26, oil flow is permitted up restricted passageway 54 around lip52. By diverting some of the oil flowing in through port 36 in thisfashion, the oil pressure in cavity 22 relative to the inlet oilpressure throughports 34 and 36 will be less. This lower pressure allowsthe desired higher speed operation in the engine. Once the oil flowreaches the intermediate area between shoulder 44 and closure element26, further flow is permitted through groove 53 formed in lip 52 intothe central opening 58 of te closure element. The flow is then directedthrough central opening 58 into the rocker arm socket 14. By carefulselection of the cross-sectional area of groove 53, the flow of oilthrough central opening 58 can be metered. Preferably, thecross-sectional area of restricted passageway 54 is greater than groove53 to assure a constant meter rate. It will be appreciated thatrestricted passageway 54 could perform the metering function. However,the length of this passageway. may vary and hence. the metering ratewould vary.

TAPPET WITH PUSH ROD Referring now in detail to FIG. 5, a tappet 16a isillustrated which is in many respects similar or identical to portionsof tappet 16 described in detail above. Therefore, correspondingelements referred to hereinafter which are similar to those describedabove will be referred to with the same numeral and the suffix a added.

Tappet 16a is designed for use in an internal combustion engineutilizing a push rod 69 cooperatively associated between a push rod seat70 movable within tappet body 18a and the rocker arm of the valve train(not shown).

The tappet 16a operates essentially the same as tappet 16 and hence thestructural recitation will not be repeated. The reference numeralshowever are provided to illustrate corresponding elements. Essentially.the only real distinction between the alternative embodiment shown inFIG. 5 from that shown in FIG. 1 is the change in the configuration ofthe closure element. Element 72 in FIG. 5 includes a push rod seatsurface 70 formed in the upper end thereof. A centrally located axiallyextending opening 58a communicates from seat 70 through the closureelement below which is positioned metering cup 46a identical to cup 46.Cup 46a rests on an internally machined shoulder 440. C10- sure element72 includes an annular shoulder 76 extending beyond the outer wall ofthe closure element for abutment against the upper end of plunger 20a.By selecting the proper axial thickness of closure element 72, the lowersurface of the closure element is spaced above shoulder 44a so thataxial movement of cup 4611 is permitted in accordance with thedescription concerning the embodiment of FIG. 1.

The operation and function of the tappet illustrated in FIG. 5 shouldthus be obvious in view of the discussion relevant to FIG. 1. Oilflowing into the tappet body through opening 34 flows through theplunger wall through inlet opening 36a. The flow is directed throughopening 36a simultaneously down into the reservoir 22a and up around lip52a in view of the outer diameter of cup 460 being less than thediameter of the plunger bore. The reservoir pressure will urge cup 46aup against the lower surface of closure element 72 and oil flowing uparound lip 52a is introducd into opening 58a in closure element 72through a groove 53a formed in the lip of cup 46a. By proper selectionof the crosssectional area of groove 530, the oil flowing through theclosure element can be properly metered. As a result of .thesimultaneous flow of oil coming through inlet opening 36a both into thereservoir 22a and up around lip 52a of cup 460, the reservoir pressureis reduced relative to the inlet pressure.

In accordance with the invention, a very simple and yet positive meansis provided for reducing the oil pressure in the reservoir to permithigher speed operation of the engine. In addition, the very means whichprovides this result also performs the metering rate for the lubricatingoil passing through the lash adjuster. The simplicity of the meteringcup described not only makes it economically inexpensive to produce, butalso provides positive assembly of the adjuster. That is, there islittle or no chance of misassembling the tappet.

Although two embodiments have been shown and described in detail, itwill be obvious to those having ordinary skill in this art that thedetails of construction of these particular embodiments may be modifiedin a great many ways without departing from the unique conceptspresented. It is, therefore, intended that the invention is limited onlyby the scope of the appended claims rather than by particular details ofconstruction shown, except as specifically stated in the claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In a hydraulic lash adjuster for an internal combustion engine havinga body; a plunger reciprocal within said body, said plunger having acentral cavity forming an oil reservoir; a lubricating oil inlet meanscommunicating with said central cavity of said plunger; a closureelement forming the upper outer portion of said plunger; and lubricatingpassage means extending from the central cavity of said plunger throughsaid closure element; the improvement comprising a cup meanspositionable in said plunger cavity beneath said closure element forreducing the pressure in said oil reservoir relative to the pressure atsaid oil inlet means, said cup means having a side wall, a bottom wall,and an open top, said top facing said closure element, said inlet meansbeing'positioned intermediate said open top and bottom wall duringoperation of said adjuster, the side wall of said cup means forming arestricted passageway from said inlet means to said cavity and furtherforming a restricted passageway from said inlet means to said closureelement such that the flow from said inlet means is divertedsimultaneously into saidreservoir and closure element thereby reducingthe oil pressure in said reservoir relative to said inlet means, saidinlet means being comprised of a first opening through said body and asecond opening through said plunger, said openings being incommunication with each other, the wall of said plunger cavity having aninner shoulder formed therein above said second opening, said cup meanshaving an outwardly projecting lip formed at its upper end, said lipbeing engageable on said shoulder whereby the wall of said cup ispositioned adjacent said second opening, the diameter of said cup beingless than said cavity wall to form said restricted passageway, and meanscomprising a longitudinal spacing between said shoulder and closureelement greater than the thickness of said cup lip, the diameter of saidlip being less than that of said cavity wall above said shoulder, theoil pressure in said reservoir urging said cup lip against said closureelement whereby said lip is clear of said shoulder, said cup lip havinga groove formed in the upper surface to form a passageway for oil flowfrom the outer surface of the lip to said central openi. The lashadjuster according to claim 1 wherein said groove with said closureelement forms a restricted flow passageway which also meters the flow ofoil to said closure element.

3. The lash adjuster according to claim 1 wherein said closure elementincludes a spherical head providing a pivot for a rocker arm, saidspherical head being receivable in a rocker arm socket, and a bodyhaving a portion receivable in said plunger.

4. The lash adjuster according to claim 1 wherein said closure elementis comprised of a push rod seat means formed in the upper end thereof.

5. A hydraulic lash adjuster having an internal cavity; an internalreservoir; oil inlet and outlet means; means communicating with said oilreservoir, inlet, and outlet means to permit flow through said adjusterwhile re ducing the reservoir pressure relative to the oil inletpressure, said means comprising a cup-shaped element positioned in saidcavity adjacent said inlet means, the wall of said cup-shaped elementduring operation of said adjuster defining a restricted passageway fromsaid inlet means to said reservoir and outlet means whereby oil flowingthrough said inlet means is directed simultaneously to said reservoirand outlet means thereby causing the oil pressure in said reservoir tohave a reduced pressure relative to the inlet pressure, the upper rim ofsaid cup-shaped element having an outwardly projecting lip positionedintermediate said inlet and outlet means, said lip including a grooveformed in the upper surface thereof, said groove with said outlet meansforming a restricted passageway for oil flow to said outlet, said groovemetering the rate of flow through said outlet.

6. In a hydraulic lash adjuster for an internal combustion engine havinga body; a plunger reciprocal within said body, said plunger having acentral cavity forming an oil reservoir; a lubricating oil inlet meanscommunicating with said central cavity of said plunger; a closureelement forming the upper outer portion of said plunger; and lubricatingpassage means extending from the central cavity of said plunger throughsaid closure element; the improvement comprising means for reducing thepressure in said oil reservoir relative to the pressure at said oilinlet means, said means for reducing the pressure in said oil reservoircomprising a cup means positionable in said plunger cavity beneath saidclosure element, said means having a sidewall and an open top, said topfacing said closure element, the sidewall of said cup means forming arestricted passageway from said inlet means to said cavity and furtherforming a restricted passageway from said inlet means to said closureelement such that flow from said inlet means is movable simultaneouslyinto said reservoir and closure element thereby reducing the oilpressure in said reservoir relative to said inlet means, said inletmeans comprising a first opening through said body and a second openingthrough said plunger, said openings being in communication with eachother, the wall of said plunger cavity having an inner shoulder formedtherein above said second opening, said cup means having an outwardlyprojecting lip formed at its upper end, said lip being engageable onsaid shoulder whereby the wall of said cup is positioned adjacent saidsecond opening, the diameter of said cup being less than said cavitywall to form said restricted passageway, said adjuster including alongitudinal spacing between said shoulder and closure element greaterthan the thickness of said cup lip, the diameter of said lip being lessthan that of said cavity wall above said shoulder, the oil pressure insaid reservoir urging said cup againstsaid closure element whereby saidlip is clear of said shoulder, said closure element includes a centralopening therethrough, said cup means lip having at least one grooveformed in the upper surface to form a restricted passageway for oil flowfrom the outer surface of said lip and closure element to said centralopening, said groove metering the rate of flow through said centralopening.

7. The lash adjuster according to claim wherein said closure element iscomprised of a push rod seat means formed in the upper end thereof.

8. In a hydraulic lash adjuster for an internal combustion engine havinga body; a plunger reciprocal within said body, said plunger having acentral cavity forming an oil reservoir; a lubricating oil inlet meanscommunicating with said central cavity of said plunger; a closureelement forming the upper outer portion of said plunger; and lubricatingpassage means extending from the central cavity of said plunger throughsaid closure element; the improvement comprising: means for reducing thethe pressure in said oil reservoir also metering the flow of oil to saidclosure element and comprising a cup means positionable in said plungercavity beneath said closure element, said cup means having a sidewalland open top, said top facing said closure element, the upper margin ofsaid sidewall having an outwardly projecting lip, said cup being urgedby the oil within said reservoir against said closure element so thatsaid lip abuts said closure element, said closure element having acentral opening therethrough, said lip having at least one groove formedin the upper surface thereof to form a restricted passageway for oilflow from the outer surface of said lip to said central opening, saidgroove metering the rate of flow to said central opening.

9. The lash adjuster according to claim 8 wherein said cup diameter isless than the diameter of said'cavity, said wall of said cup forming arestricted passageway from said inlet means to said reservoir andclosure element to reduce the oil pressure in said reservoir relative tosaid inlet means.

10. In a hydraulic lash adjuster for an internal combustion enginehaving a body; a plunger reciprocal within said body, said plungerhaving a central cavity forming an oil reservoir; a lubricating oilinlet means communicating with said central cavity of said plunger; aclosure element forming the upper outer portion of said plunger; alubricating passage means extending from the central cavity of saidplunger through said closure element; the improvement comprising: cupmeans positionable in said plunger cavity beneath said closure element,said cup means having a sidewall and open top, said top facing saidclosure element. the upper margin of said sidewall having an outwardlyprojecting lip, said cup being urged by the oil within said reservoiragainst said closure element so that said lip abuts said closureelement, said closure element having a central opening therethrough,said lip having at least one groove formed in the upper surface thereofto form a restricted passageway for oil flow from the outer surface ofsaid lip to said central opening, said groove metering the rate of flowto said central opening.

11. The lash adjuster according to claim 1.0 wherein said closureelement is comprised of a push rod seat means formed in the upper endthereof.

12. The lash adjuster according to claim 10! wherein said closureelement includes a spherical head providing a pivot for a rocker arm,said spherical head being receivable in a rocker arm socket, and a bodyhaving a portion receivable in said plunger.

1. In a hydraulic lash adjuster for an internal combustion engine havinga body; a plunger reciprocal within said body, said plunger having acentral cavity forming an oil reservoir; a lubricating oil inlet meanscommunicating with said central cavity of said plunger; a closureelement forming the upper outer portion of said plunger; and lubricatingpassage means extending from the central cavity of said plunger throughsaid closure element; the improvement comprising a cup meanspositionable in said plunger cavity beneath said closure elemEnt forreducing the pressure in said oil reservoir relative to the pressure atsaid oil inlet means, said cup means having a side wall, a bottom wall,and an open top, said top facing said closure element, said inlet meansbeing positioned intermediate said open top and bottom wall duringoperation of said adjuster, the side wall of said cup means forming arestricted passageway from said inlet means to said cavity and furtherforming a restricted passageway from said inlet means to said closureelement such that the flow from said inlet means is divertedsimultaneously into said reservoir and closure element thereby reducingthe oil pressure in said reservoir relative to said inlet means, saidinlet means being comprised of a first opening through said body and asecond opening through said plunger, said openings being incommunication with each other, the wall of said plunger cavity having aninner shoulder formed therein above said second opening, said cup meanshaving an outwardly projecting lip formed at its upper end, said lipbeing engageable on said shoulder whereby the wall of said cup ispositioned adjacent said second opening, the diameter of said cup beingless than said cavity wall to form said restricted passageway, and meanscomprising a longitudinal spacing between said shoulder and closureelement greater than the thickness of said cup lip, the diameter of saidlip being less than that of said cavity wall above said shoulder, theoil pressure in said reservoir urging said cup lip against said closureelement whereby said lip is clear of said shoulder, said cup lip havinga groove formed in the upper surface to form a passageway for oil flowfrom the outer surface of the lip to said central opening.
 2. The lashadjuster according to claim 1 wherein said groove with said closureelement forms a restricted flow passageway which also meters the flow ofoil to said closure element.
 3. The lash adjuster according to claim 1wherein said closure element includes a spherical head providing a pivotfor a rocker arm, said spherical head being receivable in a rocker armsocket, and a body having a portion receivable in said plunger.
 4. Thelash adjuster according to claim 1 wherein said closure element iscomprised of a push rod seat means formed in the upper end thereof.
 5. Ahydraulic lash adjuster having an internal cavity; an internalreservoir; oil inlet and outlet means; means communicating with said oilreservoir, inlet, and outlet means to permit flow through said adjusterwhile reducing the reservoir pressure relative to the oil inletpressure, said means comprising a cup-shaped element positioned in saidcavity adjacent said inlet means, the wall of said cup-shaped elementduring operation of said adjuster defining a restricted passageway fromsaid inlet means to said reservoir and outlet means whereby oil flowingthrough said inlet means is directed simultaneously to said reservoirand outlet means thereby causing the oil pressure in said reservoir tohave a reduced pressure relative to the inlet pressure, the upper rim ofsaid cup-shaped element having an outwardly projecting lip positionedintermediate said inlet and outlet means, said lip including a grooveformed in the upper surface thereof, said groove with said outlet meansforming a restricted passageway for oil flow to said outlet, said groovemetering the rate of flow through said outlet.
 6. In a hydraulic lashadjuster for an internal combustion engine having a body; a plungerreciprocal within said body, said plunger having a central cavityforming an oil reservoir; a lubricating oil inlet means communicatingwith said central cavity of said plunger; a closure element forming theupper outer portion of said plunger; and lubricating passage meansextending from the central cavity of said plunger through said closureelement; the improvement comprising means for reducing the pressure insaid oil reservoir relative to the pressure at said oil inlet means,said means for reducing the pressure in saId oil reservoir comprising acup means positionable in said plunger cavity beneath said closureelement, said means having a sidewall and an open top, said top facingsaid closure element, the sidewall of said cup means forming arestricted passageway from said inlet means to said cavity and furtherforming a restricted passageway from said inlet means to said closureelement such that flow from said inlet means is movable simultaneouslyinto said reservoir and closure element thereby reducing the oilpressure in said reservoir relative to said inlet means, said inletmeans comprising a first opening through said body and a second openingthrough said plunger, said openings being in communication with eachother, the wall of said plunger cavity having an inner shoulder formedtherein above said second opening, said cup means having an outwardlyprojecting lip formed at its upper end, said lip being engageable onsaid shoulder whereby the wall of said cup is positioned adjacent saidsecond opening, the diameter of said cup being less than said cavitywall to form said restricted passageway, said adjuster including alongitudinal spacing between said shoulder and closure element greaterthan the thickness of said cup lip, the diameter of said lip being lessthan that of said cavity wall above said shoulder, the oil pressure insaid reservoir urging said cup against said closure element whereby saidlip is clear of said shoulder, said closure element includes a centralopening therethrough, said cup means lip having at least one grooveformed in the upper surface to form a restricted passageway for oil flowfrom the outer surface of said lip and closure element to said centralopening, said groove metering the rate of flow through said centralopening.
 7. The lash adjuster according to claim 5 wherein said closureelement is comprised of a push rod seat means formed in the upper endthereof.
 8. In a hydraulic lash adjuster for an internal combustionengine having a body; a plunger reciprocal within said body, saidplunger having a central cavity forming an oil reservoir; a lubricatingoil inlet means communicating with said central cavity of said plunger;a closure element forming the upper outer portion of said plunger; andlubricating passage means extending from the central cavity of saidplunger through said closure element; the improvement comprising: meansfor reducing the the pressure in said oil reservoir also metering theflow of oil to said closure element and comprising a cup meanspositionable in said plunger cavity beneath said closure element, saidcup means having a sidewall and open top, said top facing said closureelement, the upper margin of said sidewall having an outwardlyprojecting lip, said cup being urged by the oil within said reservoiragainst said closure element so that said lip abuts said closureelement, said closure element having a central opening therethrough,said lip having at least one groove formed in the upper surface thereofto form a restricted passageway for oil flow from the outer surface ofsaid lip to said central opening, said groove metering the rate of flowto said central opening.
 9. The lash adjuster according to claim 8wherein said cup diameter is less than the diameter of said cavity, saidwall of said cup forming a restricted passageway from said inlet meansto said reservoir and closure element to reduce the oil pressure in saidreservoir relative to said inlet means.
 10. In a hydraulic lash adjusterfor an internal combustion engine having a body; a plunger reciprocalwithin said body, said plunger having a central cavity forming an oilreservoir; a lubricating oil inlet means communicating with said centralcavity of said plunger; a closure element forming the upper outerportion of said plunger; a lubricating passage means extending from thecentral cavity of said plunger through said closure element; theimprovement comprising: cup means positionable in said plunger cavitybeneath said closure element, said cup means having a sIdewall and opentop, said top facing said closure element, the upper margin of saidsidewall having an outwardly projecting lip, said cup being urged by theoil within said reservoir against said closure element so that said lipabuts said closure element, said closure element having a centralopening therethrough, said lip having at least one groove formed in theupper surface thereof to form a restricted passageway for oil flow fromthe outer surface of said lip to said central opening, said groovemetering the rate of flow to said central opening.
 11. The lash adjusteraccording to claim 10 wherein said closure element is comprised of apush rod seat means formed in the upper end thereof.
 12. The lashadjuster according to claim 10 wherein said closure element includes aspherical head providing a pivot for a rocker arm, said spherical headbeing receivable in a rocker arm socket, and a body having a portionreceivable in said plunger.